1. Technical Field
The present invention relates generally to foam evaporators useful for applications including the concentration of liquids. More particularly, the present invention relates to a carbon foam evaporator where the carbon foam has a bimodal pore distribution. The carbon foam evaporator exhibits improved thermal and chemical stability, high strength and low density. The invention also includes a method of use for the carbon foam evaporator.
2. Background Art
Evaporators in general are very widely used in industry for the concentration of liquids. Besides the concentration of liquids, foam evaporators serve to add volatile components to gas streams, and as an important part of many thermal conduction devices. For example, Weinrich in U.S. Pat. No. 6,755,396 describes a portable vehicle humidifier which uses a foam evaporator. A fan is mounted on top of a container with a foam pad located within the container. The foam pad is kept wet and the fan blows air across the pad and out through escape hatches. The escaping air is higher in humidity than the ambient air, so this is used to humidify mobile sources, such as the cab of a truck.
Additionally, Smith, et al., U.S. Pat. No. 6,662,802, describes a foam evaporator used to keep breathing lines free of condensation. A foam pad is placed around a heater and positioned at a low point in a breathing line. Condensation collects on the walls of the breathing line and flows down to the location of the foam evaporator. The foam evaporator then adsorbs and evaporates the condensation, keeping the breathing line free of liquids.
Further, de Juan, Jr. (U.S. Pat. No. 6,726,666) describes a foam evaporator used to humidify a gas stream used in eye surgery. During certain surgeries, the inside of an eye has to be filled with a gas. A moistened foam pad is placed within a container in the gas line which is directed to the interior of the patient's eye. This results in a humidified gas entering the patient's eye, which is useful in preventing clouding of the patient's cornea.
A two-phase thermosyphon is described by Sehmbey, et al. in U.S. Pat. No. 6,234,242. This thermosyphon includes a housing with a foam and a two-phase liquid inside the housing. Several slots are located within the foam to facilitate vapor flow. A liquid portion of the two-phase material is evaporated within the foam at the bottom of the housing and carried to the top of the housing, where it re-condenses. This transfers the heat needed to vaporize the liquid from the bottom of the housing to the top of the housing, which is beneficial in controlling the temperature of certain devices.
Alario, et al., in U.S. Pat. No. 5,303,768, describe a capillary pump evaporator. This capillary pump evaporator includes a foam evaporator with slots or grooves where a liquid is vaporized and carried away from the evaporator. This gas is then carried to a condenser where it condenses and is re-liquefied. The liquid then flows back to the foam evaporator. Heat is transferred from the foam evaporator to the condenser, which helps to control temperatures for certain devices.